update 表名 set ztime=rtime-btime where 条件其他要看下你的数据,是否要进行null的计算了
select ID , username
(select value from meta where userid=user.id and key='dlcs') as dlcs,
(select value from meta where userid=user.id and key='vp') as vp
from user
update 表名 set ztime=rtime-btime;你知道的,呵呵,试试就给加分把~!~!